Nigerian crude oil differentials held at two-year lows on Monday as demand remained subdued, partly due to high shipping costs from West Africa to Europe. Nearly half of the loading program for August, which originally had 65 cargos, was unsold on Monday. But traders said that demand might pick up temporarily later this week as traders placed cargoes for India Oil Company's import tender. High freight rates aboard suezmaxes to Europe are deterring shipments to refineries there, traders said. Rising exports of similar oil grades from Libya has also hurt demand. Libyan oil output has risen to 470,000 barrels per day (bpd) as the El Sharara oilfield ramps up, the state-run National Oil Corp (NOC) said on Sunday.